added first working main file

main.cpp

@@ -0,0 +1,39 @@
+#include <GL/glew.h>
+#include <GL/freeglut.h>
+#include <cstdio>
+
+void display() {
+    glClear(GL_COLOR_BUFFER_BIT);
+    glBegin(GL_TRIANGLES);
+    glColor3f(1.0, 0.0, 0.0);
+    glVertex2f(-0.5, -0.5);
+    glColor3f(0.0, 1.0, 0.0);
+    glVertex2f(0.5, -0.5);
+    glColor3f(0.0, 0.0, 1.0);
+    glVertex2f(0.0, 0.5);
+    glEnd();
+    glFlush();
+}
+
+void framebuffer_size_callback(GLFWwindow* window, int width, int height)
+{
+    glViewport(0, 0, width, height);
+} 
+
+int main(int argc, char** argv) {
+    glutInit(&argc, argv);
+    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
+    glutInitWindowSize(800, 600);
+    glutCreateWindow("OpenGL Example");
+    GLenum err = glewInit();
+    if (GLEW_OK != err) {
+        fprintf(stderr, "GLEW error: %s\n", glewGetErrorString(err));
+        return 1;
+    }
+
+    glViewport(0, 0, 800, 600);
+    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
+    glutDisplayFunc(display);
+    glutMainLoop();
+    return 0;
+}